Abstract: A system for transmission of an optical signal, the system including an optical coupler for splitting said signal into a first copy and a second copy. The optical coupler has an input for receiving the optical signal, a first output for the first copy and a second output for the second copy. The system also includes a first optical guide connected to the first output, a second optical guide connected to the second output and a superposition module for coherently superimposing the first copy and the second copy of the signal.

Abstract: A system for transmission of an optical signal, the system including an optical coupler for splitting said signal into a first copy and a second copy. The optical coupler has an input for receiving the optical signal, a first output for the first copy and a second output for the second copy. The system also includes a first optical guide connected to the first output, a second optical guide connected to the second output and a superposition module for coherently superimposing the first copy and the second copy of the signal.

Abstract: An all-optical signal regeneration technique in which a modulation alphabet is mapped on to a set of optimised points of a regenerative transfer function. The optimised points correspond to attraction regions in the regenerative transfer function and are preferably stable. The regenerative transfer function can be selected to be the Fourier transform of an ideal regenerator, which is represented by a step-wise transfer function. Use of the Fourier transform can enable efficient regeneration of multilevel multidimensional signals. The regenerative Shannon limit—the upper bound of regeneration efficiency can also be derived.

Abstract: Communication transmission system and method are disclosed based on introducing a large pre-dispersion of optical signal before launching the signal into an uncompensated communication system. The pre-dispersion has the same sign as dispersion of a transmission fibre. The aim of the method is to improve the transmission quality and simplify the digital signal mitigation of nonlinear impairments after the transmission. In the preferred embodiment, the optical system is a coherent communications system with any symbol rate, modulation format and/or carrier wavelength.